New Chinese Pterosaur Track – It’s Chaoyangopterus!

A new paper by Chen et al. (2013) illustrates new early Late Cretaceous pterosaur tracks (Fig. 1). The manus print was outlined before publication.

New pterosaur tracks by Chen et al. 2013.

Figure 1. New pterosaur tracks by Chen et al. 2013.

The new tracks are notable.
The pes is narrow and digits 2-4 are aligned transversely. The manus impression is relatively large with wide angles between the fingers.

Figure 2. Based on faint impressions in the pterosaur tracks the joints have been drawn and PILs have been added.

Figure 2. Based on faint impressions in the pterosaur tracks the joints have been drawn and PILs have been added. Toe drag marks in green. Small circles on manus represent distal ends of metacarpals 1-3. There is no trace of the big wing finger here. Pedal digit 1 either hit a hard patch or was elevated as it did not make much of an impression.

Pteraichnus dongyangensis Holotype: Manus: DYM-04666-1; Pes: DYM 04666-3. The diagnosis of the manus print is based on the finger angles. The pes is based on a width to length ratio of 17 percent. Chen et al. (2013) note the pes print is 9 cm long, but that includes the toe drag marks.

Figure 3. Scaled to the tracks, the pes and manus of Chaoyangopterus are added.

Figure 3. Scaled to the tracks, the pes and manus of Chaoyangopterus are added. It’s a pretty good match. It’s a damn good match! Pedal digit 1 makes little to no impression.

It’s good to have a catalog of pterosaur pedes (Peters 2011) to compare tracks to. Here Chaoyangopterus appears to be a great match, even down to the scale bars and chronology!

Figure 1. Chaoyangopterus alongside the new China tracks from the early Late Cretaceous.

Figure 4. Chaoyangopterus

Chaoyangopterus is a pre-azhdarchid pterosaur with relatively small and narrow plantigrade feet. Seems to be a good match in nearly every aspect.

References
Chen R-J, Lü J-C, Zhu Y-X, Azuma Y, ZhengW-J, Jin X-S, Noda Y and Shibata M 2013. Pterosaur tracks from the early Late Cretaceous of Dongyang City, Zhejiang Province, China. Geological Bulletin of China 32(5): 693-698. Free online.
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos, 18: 2, 114 —141

Tiny pterosaurs – breaking the short rostrum false paradigm

With the false paradigm still in force among professional paleontologists that juvenile pterosaurs all have a short rostrum and a large orbit (Witton 2013 and references therein, like birds and crocs and mammals), it’s worthwhile to take a look at several tiny pterosaurs, each with a long rostrum. Each has been nested phylogenetically in the large pterosaur tree, the only effort, so far, to nest the tiny ignored ones. 

Here are nine tiny taxa, each with a fairly long – to extremely long – rostrum
Seven are found without an eggshell present (Figs. 1-7). Whether these are hatchlings, juveniles or adults cannot be determined except by their phylogenetic nesting. If sister taxa are large, then it’s more likely that these are juveniles. However, 1-7 are all surrounded by or nest next to tiny taxa. They also all nest after a series of larger taxa and prior to another series of larger taxa that all establish new clades. This is how pterosaurs evolved new clades.

Two others are embryos surrounded by eggshells (Figs. 8-9). Both of these are phylogenetically surrounded by large taxa.

Figure 1. I didn't realize the teeth were so long in ?Pterodactylus spectabilis, TM10341, n1 in the Wellnhofer 1970 catalog. This is no Pterodactylus, but a tiny dorygnathid. Click to learn more.

Figure 1. ?Pterodactylus spectabilis, TM10341, n1 in the Wellnhofer 1970 catalog. This is no Pterodactylus, but a tiny dorygnathid. Click to learn more.

TM 10341 nests between a much larger Dorygnathus (SMNS 50164) and slightly larger Rhamphodactylus BSPG 2011 I 133.

Figure 2. BSp 1968 XV 132

Figure 2. BSp 1968 XV 132 nests with Cycnorhamphids and tiny scaphognathids. Click to learn more.

BSp 1968 XV 132 nests between the smaller GMU 10157 and the equally small, BSt 1936-I-50 no. 30 (Fig. 3), close to cycnorhamphids.

B-St-1936-I-50-no30

Figure 3. B-St-1936-I-50 no. 30. Click to learn more.

BSt 1936 I 50 (no. 30 in the Wellnhofer 1970 catalog) nests with BSp 1968 XV 132 (Fig. 2).

MB.R.3530.1-(No.40)

Figure 4. MB.R.3530.1-(No.40) basal to ctenochasmatids

MB.R.3530.1 (No.40) nests between the equally tiny St/Ei I (derived from the larger Angustinaripterus) and ?Ctenochasma elegans (AMNH 5147, Fig. 5).

AMNH 5147

Figure 5. AMNH 5147, basal to ctenochasmatids

AMNH 5147 nests between tiny MB.R.3530.1 (Fig. 4) and larger Gnathosaurus.

Pterodactylus? elegans? BSPG 1911 I 31 (no. 42 in the Wellnhofer 1970 catalog)

Figure 6. Pterodactylus? elegans? BSPG 1911 I 31 (no. 42 in the Wellnhofer 1970 catalog). Click to learn more. Basal to azhdarchids, distantly derived from no. 1 (Fig 1.)

BSPG 1911 I 31 (no. 42 in the Wellnhofer 1970 catalog) nests between CM 11426 (no. 44 in the Wellnhofer 1970 catalog) and Sos 2428, the flightless pterosaur on one branch and the pro to-azhdarchid, Jidapterus, on the other branch.

Senckenberg-Museum Frankfurt a. M. No. 4072

Figure 7. Senckenberg-Museum Frankfurt a. M. No. 4072. Click to learn more.

Senckenberg-Museum Frankfurt a. M. No. 4072 (no. 12 in the Wellnhofer 1970 catalog) nests between the smallest pterosaur, B St 1967 I 276 (No. 6 of Wellnhofer 1970) and a larger specimen, B St ASXIX 3 (plate) SMF No. R 404 (counterplate), No. 23 of Wellnhofer 1970). No. 6 had a smaller snout and larger rostrum because it was more closely related to tiny Ornithocephalus and the larger Scaphognathus (no. 110), and the even larger Scaphognathus (no. 109). See all of these in one image here.

And now, the embryos:

JZMP-03-03-2

Figure 8. JZMP-03-03-2 embryo shown with hypothetical 8x larger adult and sister taxa scaled to the adult. Click to learn more and see detailed imagery of the embryo in the eggshell.

Misinterpreted as a Beipiaopterus, the embryo JZMP-03-03-2 nests between the basal ornithocheirids, Yixianopterus and Haopterus (Fig. 8). An adult of the embryo would be twice the size of Haopterus 

Pterodaustro embryo

Figure 9. Pterodaustro embryo. There certainly is no short snout/large eye here! However there are several differences between this specimen and the adult. Click to learn more.

The Pterodaustro embryo nests with its parent, Pterodaustro and this lineage disappears after this taxon. There are slight differences between the embryo and adult Pterodaustro. There are differences between adult Pterodaustro, detailed here.

Certainly there are embryos and tiny pterosaurs with a short rostrum and large orbit (like the IVPP embryo which is the size of other adult anurognathids!). All sister taxa likewise have a short rostrum and large orbit and other similar traits detailed here.

Earlier we looked at a hypothetical Quetzalcoatlus sp. embryo tucked into a long shell to accommodate that long rostrum. Pterodaustro likewise produced an elongated egg to accommodate that hyperelongated rostrum.

References
Click to each taxon for additional references.

Scathing Book Review – Pterosaurs by Witton (2013) – the Darwinopterus blunder

Earlier we looked at the myth of Darwinopterus as the transitional taxon between long-tailed early pterosaurs and short-tailed later pterosaurs. Actually, several series of tiny pterosaurs (Fig. 5 as an example) fill that role and they do it four times, two out of two distinct Dorygnathus and two out of the smallest Scaphognathus (which is why some tiny pterosaurs have a large eye and short snout).

Remember a good transition consists of a beginning, several middles and an end. The Darwinopterus scenario provides a middle, but no specific beginning or end.

Darwinopterus and associated egg.

Figure 1. Darwinopterus female and associated egg.

Supporting the traditional view, Mark Witton, author of “Pterosaurs“, reports, Darwinopterus incontrovertibly fills a long-standing gap in pterosaur evolution, bridging the morphological distance between early pterosaurs and Pterodactyloidea.”

Incontrovertibly? Not so. Darwinopterus fails when put to several tests (see below).

Witton (2013) also falls off the Darwinian train when he reports, “Rather than demonstrating a bauplan with a smattering of pterodactyloid and non-pterodactyloid features across the entire skeleton, it [Darwinopterus] possess the characteristic skull and neck of pterodactyloid while retaining a body very similar to those of rhamphorhynchid pterosaurs.” This has been called, “modular evolution” and this is the only animal that this bizarre mode of evolution has _ever_ been applied to. Modular evolution creates chimaeras, but that’s _not_ how evolution works!

Long time readers of the Pterosaur Heresies already know the solution to this problem.

According to the results of the large pterosaur tree (now 204 taxa), Darwinopterus nests at the acme of a small clade of darwinopterids including Wukongopterus, Kunpengopterus and Pterorhynchus at its base, all derived from a sister to Jianchangnathus, which also gave rise to Scaphognathus and a long list of tiny and large descendants.

A clade has been erected (Lü, Unwin, et al. 2009) for Darwinopterus + Pterodactyloidea, the “Monofenestrata.” Unfortunately, Darwinopterus does not have a monofenestra. The naris is small, but still visible (Fig. 2), just like Pterorhynchus.

Figure 2. Click to enlarge. Darwinopterus skull with colorized rostral bones. The arrow points to the naris, still present.

Figure 2. Click to enlarge. Darwinopterus skull with colorized rostral bones. The arrow points to the naris, still present. This is just a big, long-necked basal scaphognathid.

More unfortunately, Darwinopterus does not nest near the base of any pterodactyloid-grade pterosaurs in the completely resolved large pterosaur tree. Those taxa that do actually nest at the base of pterodactyloid-grade pterosaurs (in the large pterosaur tree) fulfill Witton’s wish for a smattering of pterodactyloid and non-pterodactyloid features. Those features can be found in tiny pterosaurs (Fig. 5).

 Pterosaur family tree according to Witton (2013). Note all of the suprageneric taxa here! That means Witton does not have to come up with an ancestor to Darwinopterus nor a descendant. The large pterosaur tree provides specific specimens for both.

Figure 3. Pterosaur family tree according to Witton (2013). Note all of the suprageneric taxa here! That means Witton does not have to come up with a specific ancestor to Darwinopterus nor a descendant. The large pterosaur tree provides specific specimens for both.

Let’s put aside all the other problems with Witton’s pterosaur family tree and focus on the Darwinopterus situation.

Here Darwinopterus nests within the Wukongopteridae, a suprageneric taxon. Both the ancestor and descendant taxa are also suprageneric, leaving the transition to and from Darwinopterus rather cloudy. By that I mean, Witton doesn’t tell us which taxa are the direct ancestors and descendants of Darwinopterus. That avoids having to deal with details and data. Actually the original Lü, Unwin et al. (2010) tree generated some 500,000 most parsimonious trees, so from the start there are red flags everywhere with this study and this tree.

By contrast
there’s complete resolution (one tree results) in the large pterosaur tree. It also provides specific taxa (specimens) that nest with Darwinopterus and others that act as transitions to the four pterodactyloid grades. The former clade “Pterodactyloidea” is not monophyletic when tiny pterosaurs are included in analysis, something Witton and his cohorts refuse to do.

For a reminder, here (Fig. 4) are the closest sisters to Darwinopterus and three Darwinopterus specimens. The upper clade of wukongopterids are monophyletic, not transitional. The real story takes place after Scaphognathus with those half-sized descendants (no, they’re not juveniles).

Figure 1. Darwinopterids and their closest sisters in phylogenetic order beginning with Sordes.  Click to enlarge.

Figure 4. Click to enlarge. Darwinopterids (wukongopterids) and their closest sisters in phylogenetic order beginning with Sordes. Kunpengopterus is derived from Pterorhynchus. Darwinopterus and Wukonopterus were derived from Kunpengopterus. So the skull gradually increases in length along with the neck.

And here (Fig. 5)  are some of the transitional taxa arising out of the small Scaphognathus specimens. These tiny pterosaurs are the real transitional taxa. And there’s not just one. There are four series with gradual decreases and gradual increases in size. The hope that there is just one transitional taxon is a myth. The transition is a spectrum of gradual change. The apparent disappearance of the naris likewise had four paths with some reducing the naris and others merging the naris and antorbital fenestra.

Scaphognathians

Figure 5. Click to enlarge. Scaphognathus and its tiny descendants that ultimately gave rise to larger descendants.

Here, using specimens, you can see that every specimen between the large Scaphognathus and the large Germanodactylus are transitional taxa, creating a spectrum, some closer to Scaphognathus and others closer to Germanodactylus. That’s the beauty of using specimens, rather than suprageneric taxa. You get the real picture without any fudging or imagination.

By convergence, Darwinopterus, like the other four gradual transitions, did reduce the naris and elongate the skull and neck. These traits were derived from Pterorhynchus, which already had a reduced naris, then Kunpengopterus, which had a longer skull and longer neck (Fig. 4).

But then Darwinopterus went nowhere. It became extinct. End of story?

Let’s hope.

References
Lü J, Unwin DM, Jin X, Liu Y and Ji Q 2009. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of the Royal Society London B  (DOI 10.1098/rspb.2009.1603.)
Lü J, Unwin DM, Deeming DC, Jin X, Liu Y and Ji Q 2011a. An egg-adult association, gender, and reproduction in pterosaurs. Science, 331(6015): 321-324. doi:10.1126/science.1197323
Lü J, Xu L, Chang H and Zhang X 2011b. A new darwinopterid pterosaur from the Middle Jurassic of Western Liaoning, northeastern China and its ecological implicaitions. Acta Geologica Sinica 85: 507-514.
Witton M. 2013. Pterosaurs. Princeton University Press. 291 pages.

wiki/Darwinopterus

Scathing Book Review – Pterosaurs (Witton 2013) – Rhamphorhynchus problems

Earlier here, here and here we looked at various problems with Mark Witton’s new book, entitled Pterosaurs. The basic problem is he doesn’t test past hypotheses with phylogenetic analysis and accurate reconstructions. He merely accepts the literature (make that most of the literature).

More grist for the mill.
Today we’ll continue exposing yet another in a long series of false hypotheses presented in Witton’s “Pterosaurs”. Today’s topic: pterosaur growth patterns.

Allometric growth in pterosaurs is false
In many vertebrates the hatchlings and juveniles have different proportions than the adults. We see this allometric growth in birds, humans and ichthyosaurs among many others. However, this is not a universal trait. We don’t see it in pterosaurs, despite Witton’s illustration of it (Fig. 1). Earlier we talked about pterosaur growthfusion patterns and pterosaur embryos.

Rhamphorhynchus growth according to Witton, Bennett and Wellnhofer.

Figure 1. Rhamphorhynchus growth according to Witton, Bennett and Wellnhofer. This is not based on phylogenetic analysis, but the assumption was made that all these are conspecific. “Little” in this case, does not necessarily mean “young” but these workers assumed that it did.

Here’s an illustration taken from Witton (2013) that was essentially copied from Wellnhofer (1991) in which Witton shows that small Rhamphorhynchus changed as they grew into adults, following the hypothesis of Bennett (1995). Unfortunately there’s little to no critical thinking here. This could be, and is, closer to a phylogenetic series. Compare these illustrations with the more precise, complete  and ordered Rhamphorhynchus illustrations (Fig. 2-3) and note those scale bars.

Isometric growth in pterosaurs is based on evidence
Some clades experience isometric growth in which hatchlings and juveniles greatly resemble their full-grown counterparts. Pterosaurs and their ancestors going back at least to the basal lepidosaur, Huehuecuetzpalli (Reynoso 1998), are among those, as determined by embryos (like Pterodaustro) and juveniles (like Zhejiangopterus) that greatly resemble their larger adult counterparts. Hatchling pterosaurs don’t have a large orbit and a short rostrum (unless their parents share those traits!). So, what we have below (Figs. 2, 3) are adult pterosaurs, no matter their size. And if they are anything younger than adult, that’s okay. Juveniles were virtually identical to adults.

Figure 2. The evolution of Rhamphorhynchus part 1. Here, starting with Campylognathoides (the Pittsburgh specimen) this lineage experiences a size reduction down to Bellubrunus, then the rostrum elongates and the size increases to the giant of the Rhamphorhynchus clade, no. 81.

Figure 2. The evolution of Rhamphorhynchus part 1. Here, starting with Campylognathoides (the Pittsburgh specimen) this lineage experiences a size reduction down to Bellubrunus, then the rostrum elongates and the size increases to the giant of the Rhamphorhynchus clade, no. 81. The details are important! Even the pedal proportions change.

In the above series representing the first half of Rhamphorhynchus evolution we can see the derivation from Campylognathoides, the reduction of the rostrum as the adults became smaller and smaller, followed by the elongation of the rostrum in more derived forms.

The largest Rhamphorhynchus (Iowest image in Fig. 2) does not represent the end of the line. The second half of this clade is shown below as refinements in smaller species continue (see Fig. 3).

Figure 3. Rhamphorhynchus evolution. part 2. Following the giant no. 81, these rhamphs were all about half of its size yet display derived traits leading to the last of this clade, no. 52. The details are important!

Figure 3. Rhamphorhynchus evolution. part 2. Following the giant no. 81, these rhamphs were all about half of its size yet display derived traits leading to the last of this clade, no. 52. The details are important!

See what problems you can get into?
By not even testing tiny pterosaurs and by not even testing several Rhamphorhynchus specimens in phylogenetic analysis, Witton (2013) has assumed a growth series based on size alone. This is wrong, according to a phylogenetic analysis (Fig.s 2, 3) that demonstrates several times the pattern of pterosaurs shrinking in size at the bases of several new clades before their descendants later increased in size as adults. Tiny pterosaurs have been unfairly maligned and ignored as juveniles when they need to be included in analyses in order to see the complete picture of pterosaur evolution.

Earlier we looked at the variation in the feet of Rhamphorhynchus species that help determine these are not growth series examples. You can see several examples here (Figs 2-3).

I haven’t seen any small Rhamphorhynchus specimens that resemble or nest with larger ones. That suggests juvenile specimens survived in different environments and did not fossilize along with the others in the Solnhofen basins.

Red Flag went unnoticed
In Witton (2013, figure 13.3) the caption reads, “C. large adult stage. The last stage is particularly rare, being represented by only two specimens.” Out of hundreds of specimens, only two are adults? That’s a red flag. Where is the critical thinking? Where is the phylogenetic analysis? Where are the detailed reconstructions based on precise tracings?

If an amateur can figure this out, why can’t a professional? Take Witton’s pterosaurs as traditional thinking that is currently under revision. Large parts of it do not represent the best current evidence.

References
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen limestone of Germany: year classes of a single large species. Journal of Paleontology 69, 569–580.
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.
Witton M. 2013. Pterosaurs. Princeton University Press. 291 pages.

wiki/Rhamphorhynchus

Nicknamed “Rhamphodactylus” – Is it a Transitional Pterosaur?

Last year Rauhut (2012) published on a new pterosaur, BSPG 2011 I 133, now being nicknamed, “Rhamphodactylus,” in honor of its purported transitional status between rhamphorhynchoids and pterodactyloids.

We learned earlier than neither term is monophyletic.

Rhamphorhychoids, as everyone knows, are simply basal pterosaurs and they “stop” being rhamphorhynchoids when some evolve pterodactyloid traits.

The pterodactyloid grade had four origins, two out of Dorygnathus and two out of Scaphognathus (itself a dorygnathid).

Darwinopterus and kin developed several pterodactyloid traits, but they were a dead end, producing no known descendants in the Cretaceous, according to the results of the large pterosaur tree.

Figure 1. Rhamphodactylus in situ, colors applied to identify bones. See reconstruction. Scale bar is 3 cm. The short tail (closeup in figure 5) is just to the left of the scale bars.

Figure 1. Rhamphodactylus in situ, colors applied to identify bones. See reconstruction. Scale bar is 3 cm. The short tail (closeup in figure 5) is just to the left of the scale bars.

Rauhut (2012) mentions the well known traits of the pterodactyloid grade:

  1. short tail
  2. coalesced naris/antorbital fenestra
  3. longer neck and
  4. longer metacarpal.

He lists Darwinopterus (Middle Jurassic, China) and another South American form based on scraps as pterosaur transitional taxa. To these he adds the new specimen (Figs. 1-5). No phylogenetic analysis was performed for the short paper.

Figure 2. Rhamphodactylus skull. Note the large antorbital fenestra. Maxilla

Figure 2. Rhamphodactylus skull. Note the large antorbital fenestra. Maxilla

It would be certainly tempting
to consider “Rhamphodactylus” a transitional taxon, but we already have four well-established transitional series, all made up of tiny taxa. The fact that traditional pterosaur workers continue to refuse to add tiny pterosaurs to their analyses means they will never know the path or mechanism for pterosaur evolution. “Rhamphodactylus” is on the small side (Fig. 6). So, perhaps it will open the door for other tiny pterosaurs to be studied and recognized as tiny adults.

Despite hopes
The new taxon, it turns out, merely fills the gap between tiny TM 10341 and Beipiaopterus + CM  11426 (Fig. 6), so all three are pterodactyloid-grade pterosaurs. This is a dorygnathid-like skull, but the teeth are reduced, a characteristic of this clade that ultimately produced toothless azhdarchids. Moving “Rhamphodactylus” to the darwinopterids adds 11 to 18 steps. Moving “Rhamphodactylus” one node closer to Dorygnathus adds 4 steps.

Rhamphodactylus manus

Figure 3. Rhamphodactylus manus

Rauhut (2012) notes “Rhamphodactylus” (Upper Jurassic) has a metacarpal length exactly between the statistical cloud of rhamphs and pterodacs. For such details it’s worthwhile to check out accurate reconstructions of its sister taxa (Fig. 6) both of which have the shortest metacarpals of all pterodactyloid-grade pterosaurs. Other transitional taxa all had relatively longer metacarpals.

Figure 4. Rhamphodactylus reconstructed. Yes, there's a possible skull at 1/8 the size of the adult specimen near the tail.

Figure 4. Rhamphodactylus reconstructed. Yes, there’s a possible skull at 1/8 the size of the adult specimen near the tail.

Reconstruction of “Rhamphodactylus.”
The study of roadkill specimens benefits greatly from a reconstruction (Fig. 4), but rarely occurs. “Rhamphodactylus” retains the maxillary notch present in Dorygnathus and TM 10341 and provides clues as to the morphology of the unknown skull of Beipiaopterus. Reconstructing the foot is also highly diagnostic.

Figure 5. Abbreviated tail of "Rhamphodactylus" along with a possible aborted embryo at 1/8 the size of the adult.

Figure 5. Abbreviated tail of “Rhamphodactylus” along with a possible aborted embryo at 1/8 the size of the adult. Since the last caudal retains a chevron, my guess  is the tail continues on in reduced form, curling right (dashed green line) then back toward the base where it terminates in loose strands (upper right). The rest of the tail is either lost or buried or both.

Is BSPG 2011 I 133 a mother?
I would encourage the preparators of “Rhamphorhynchus” to be especially vigilante around the tail as there appears to be a possible embryo skull there, aborted during taphonomy. Then again, those indications could represent preparation marks.

Figure 5. Click to enlarge. Rhamphodactylus and kin.  Dorygnathus SMNS 50164, TM 10341, Rhamphodactylus, Beipiaopterus and CM 11426 to scale

Figure 6. Click to enlarge. Rhamphodactylus and kin. Left to righ: Dorygnathus SMNS 50164, TM 10341, Rhamphodactylus, Beipiaopterus and CM 11426 to scale.

According to the large pterosaur tree, “Rhamphodactylus” nests close to Dorygnathus (SMNS 50164 specimen) between TM 10341 and Bepiaopterus and CM 11426. It is certainly a transitional taxon, as all of these taxa are, but it represents the size increase portion of the lineage.

Pterodactyloid-grade traits were already present in tiny TM 10341, which has been known for decades, but has been largely ignored and considered a juvenile or hatchling. TM 10341 is closer to the transitional point. lt has a shorter neck, shorter metacarpus and shorter skull. This is the lineage (Fig. 6) that ultimately produced flightless waders and giant azhdarchids.

The other dorygnathid lineage emphasized the teeth and produced ctenochasmatids.

The two scaphognathid clades reduced the rake-like teeth and produced cycnorhamphids + ornithocheirids on one branch and pterodactylids + germanodactylids and their larger descendants on the other.

It’s nice to celebrate the finding of new transitional taxa,
but let’s remember the real transitional taxa have been known for decades, if not centuries. Let’s not ignore them any longer. Traditional paleontologists won’t appreciate this news. It exposes their oversights and the discoveries that should have been theirs’ but now have fallen into the hands of amateurs. Discoveries are celebrated. Requests for speaking engagements and IMAX appearances can turn on a good run of discoveries.

On the other hand,
being embarrassed in paleontology by a run of false discoveries often turns into a good ole’ Amish shunning, or “Meidung”, the German word for avoidance. Today the only problem with Meidung in professional paleontology is the purposeful avoidance of good data and more parsimonious results based on larger inclusion sets. Pterosaur authors like Hone, Unwin and Witton who avoid looking at tiny pterosaurs and fenestrasaurs in phylogenetic analyses are running the risk here and I encourage them to take their blinders off.

References
Rauhut OWM 2012. Ein “Rhamphodactylus” aus der Mörnsheim-Formation von Mühlheim. Freunde der Bayerischen Staatssammlung für Paläontologie und Historische Geologie e.V., Jahresbericht und Mitteilungen 01/2012; 40:69-74.  online here.

News story in German

Scathing Book Review – Pterosaurs (Witton 2013) – Dimorphodon problems

Updated June 10, 2015 with a revised Dimorphodon takeoff  (Fig. 3) that included a downstroke right at the start of the leap. 

Earlier we looked at the inaccurate cartoon produced of the hind-wing glider, Sharovipteryx by author and illustrator, Mark Witton.  Here we’ll continue up the phylogenetic line to consider the disfigurements Witton applied to a basal pterosaur.

As a purported pterosaur expert, Mark Witton, author of the new book “Pterosaurs,” should be able to accurately portray a pterosaur skeleton. Unfortunately his Dimorphodon drawing is filled with errors (Fig. 1). For comparison, an accurate portrayal based on a bone-by-bone tracing is shown below (Fig. 4).

Dimorphodon by Mark Witton, filled with errors.

Figure 1. Dimorphodon by Mark Witton, filled with errors. This pose does allow Witton to avoid the digitigrade and bipedal issues, which would be visibly odd if set in a standing pose. Is there any way this pterosaur could complete a pushup that would launch it into the air high enough to unfold that big wing finger before crashing to Earth. This is a risky move every time it’s attempted!

  1. Apparent mandibular fenestra – caused by a slipped surangular detailed here and confirmed by Bennett (2013).
  2. All pterosaurs have eight cervicals (prior to ninth vert with deep ribs)
  3. 1st and 2nd dorsal ribs should be hyper-robust and 2nd articulates with sternal complex
  4. Prepubis is the wrong shape and should articulate with the ventral pubis at its stem and against the edges of the last gastralia at its anterior process
  5. Caudal vertebrae should align with the sacrals with neural spines rising above the ilium
  6. The radius in all tetrapods originates on the lateral humerus, not the medial
  7. The pteroid should originates on the proximal carpal, not the preaxial carpal (Peters 2009, Kellner et al. 2012)
  8. Metacarpals 1-3 should align palmar sides down, out and away from metacarpal 4. This provides room for all four metacarpals to have extensors tendons.
  9. Following a wrong hypothesis, Witton orients his pterosaur fingers posteriorly, but all pterosaur tracks show digits 1-2 were oriented laterally and only digit 3  oriented posteriorly due to a spherical metacarpophalangeal joint, as in many lizards.
  10. Pedal digit 5 never flexes at pedal 5.1 (Fig. 1), but does flex nearly 180 degrees at pedal 5.2 in fossils (Fig. 4). Witton disfigured toe 5 this way in order to have it frame a uropatagium, as has been suggested for Sordes and MSNB 8950, but both are misinterpretations detailed here and here. The actual orientation of pedal digit 5 is detailed in Peters (2000, 2011, Fig. 4) and here and here.
  11. The tail and torso both appear to be too short. Freehanding, like Witton does, is not conducive to accuracy.

Forelimb pterosaur leaping
One of the hypothetical practices Witton endorses for pterosaurs across the board is the much promoted, but wisely criticized, forelimb launch. We’ve discussed its failing before. There is still no evidence for it in the fossil record, although Witton pins his hopes on a three-year-old rumor. Witton illustrates nearly all of his pterosaurs in the forelimb launch configuration (fig. 1). What Witton doesn’t show is what happens shortly thereafter. Here (Fig. 2) is Witton’s Dimorphodon trying to become airborne after attempting a mighty pushup with folded wings beneath its body and mighty triceps extensors working their hearts out. Forelimb leaping is also tremendously difficult for athletes as seen here. Click the image (Fig. 2) to animate it if not already animated.

Click to animate. Witton's Dimorphodon in the process of leaping. Note the wings are in the upswing at the apex of the leap. The opposite and equal reaction, along with gravity, pushes the pterosaur down. There's just not as much leverage and musculature here as in the vampire bat, which can accomplish this leap.

Figure 2. Click to animate. Witton’s Dimorphodon in the process of leaping. Note the wings are in the upswing at the apex of the leap. The opposite and equal reaction, along with gravity, brings the pterosaur down. There’s just not as much leverage and musculature here as in the vampire bat, which can accomplish this leap. Human athletes cannot get this high. At the apex of this leap the wings are just beginning to unfold. Moreover those big wing fingers have to swing through a ventral arc before swinging above the torso prior to the first wing beat. Finally, there’s not much forward thrust here.

There has always been a better way for Dimorphodon to leap (Fig. 3), like a leaping lizard and the vast majority of all tetrapods: by using the hind limbs, like birds, frogs and kangaroo rats do.

Figure 3. Click to animate. Dimorphodon hind limb leap - like a bird or a frog. There's nothing wrong with this method. It gets the wings open right away to provide thrust and lift at the apex of the hind limb portion of the leap. The thighs are massively muscled, more so than the forelimbs. The extension and flexion of the toes provide that last little umph! to the take-off, as in frogs and kangaroo rats. And let's remind ourselves, pterosaurs were fully capable of bipedalism and leaping, as shown here.

Figure 3. Click to animate. Dimorphodon hind limb leap – like a bird or a frog. There’s nothing wrong with this method. It gets the wings open right away to provide thrust and lift at the apex of the hind limb portion of the leap. The thighs are massively muscled, more so than the forelimbs. The extension and flexion of the toes provide that last little umph! to the take-off, as in frogs and kangaroo rats. And let’s remind ourselves, pterosaurs were fully capable of bipedalism and leaping, as shown here.

Exceptions include tiny vampire bats (Fig. 4) which arrived at forelimb leaping secondarily, as a bi-product of their lifestyle and the extremely weak legs of bats in general. Primates, jumping rodents and flying lemurs are much better at hind limb leaping than bats are. Click here to see the video of the top 10 fastest, highest jumping animals.

Figure 3. Dimorphodon and Desmodus (the vampire bat) compared in size. It's more difficult for larger, heavier creatures to leap, as the mass increases by the cube of the height. Size matters. And yes the tail attributed to Dinmorphodon, though not associated with the rest of the skeleton, was that long. Note the toes fall directly beneath the center of balance, the shoulder glenoid, on this pterosaur, And it would have been awkward to get down on all fours.

Figure 4. Dimorphodon and Desmodus (the vampire bat) compared in size. It’s more difficult for larger, heavier creatures to leap, as the mass increases by the cube of the height. Size matters. And yes the tail attributed to Dinmorphodon, though not associated with the rest of the skeleton, was that long. Note the toes fall directly beneath the center of balance, the shoulder glenoid, on this pterosaur, And it would have been awkward to get down on all fours.

Size matters!
Dimorphodon is not a large pterosaur. Even so, it is several times larger than a vampire bat (Fig. 4). Its not just the effect of gravity, which increases with the cube of height, but it’s also the cushion of air, that becomes so much more cushiony the smaller a creature gets and as it adds surface area. That’s why vampire bats can get away with forelimb leaping while pterosaurs larger than a vampire bat likely could not. And giraffe-sized pterosaurs could probably leap with their forelimbs about as high as a giraffe can leap with its forelimbs.

At least he’s consistent
Witton incorrectly pastes dorsal metacarpals 1-3 back-to-back against metacarpal 4 (now rotated palmar side posterior to enable wing folding, Fig. 1). That orients the free fingers palmside anterior during flight and all posteriorly when hyperextended during terrestrial locomotion (Fig. 1). Unfortunately that doesn’t match pterosaur handprints, which are lateral for digits 1 and 2 (sometimes anterior for digit 1) and posterior for digit 3 due to a spherical joint there. That also means when a pterosaur wants to clamber up a tree, it can’t because in Witton’s view the palms are face up, as if begging.

The better orientation is palm side down while flying (or palms medial (like clapping) when walking). That also gives all four forelimb digits plenty of room to have extensor tendons. The preferred configuration also means the fingers hyperextend laterally when walking with the exceptional digit 3 oriented backwards to match ichnites. Details here.

But not always consistent
Witton’s figure 7.10 has the palms facing each other while the pterosaur is floating. They should be palms up in his view.

Whether pterosaurs had their fingers oriented laterally or posteriorly, that’s arrived at secondarily, because no tetrapods do this plesiomorphically. Their fingers always point in the direction of travel. The secondary lateral placement of the fingers on the substrate occurred after a bipedal phase shown in Cosesaurus/Rotodactylus and emphasized in Sharovipteryx. In Witton’s hypothetical scenario, the one that ignores real fossils, pterosaurs and their ancestors were never bipeds.

Pterodactylus walk matched to tracks according to Peters

Figure x. Click to animate. Plantigrade and quadrupedal Pterodactylus walk matched to tracks

No Bipedal Footprints?
Along with the adoption of the forelimb launch, Witton (2013) rejects the bipedal capabilities of pterosaurs, first promoted by Padian (1983) and later by Peters (2000a, b, 2011). Peters (2000a, b) recognized that pterosaur tracks known at that time were all plantigrade and quadrupedal but recognized that pterosaurs anatomy could vary and that even the quadrupdal pose included having the toes directly beneath the center of gravity, the shoulder glenoid (Fig. x). That enabled the forelimbs to be raised without changing elevating the back. Witton ignored this data. He also reports there are no records of digitigrade pterosaurs, but his book includes an illustration of one (his figure 7.9) and he ignores the several digitigrade pterosaurs in other published works (Peters 2011, Fig. 5) mentioned, referenced and illustrated here, here, herehere and here.

Digitigrade pterosaur tracks

Figure 5. A pterosaur pes belonging to a large anurognathid, “Dimorphodon weintraubi,” alongside three digitigrade anurognathid tracks and a graphic representation of the phalanges within the Sauria aberrante track. Digit 5 impressing far behind the other toes is the key to identifying tracks as fenestrasaurian or pterosaurian.

Not Digitigrade? It pays to be specific here.
Witton referenced Clark et al. (1998) who reported that basal pterosaurs, like Dimorphodon, had flat feet because they could not bend the metatarsophalangeal joint due to the squared-off (butt joint) shape. Peters (2000a) showed that Cosesaurus, an ancestor to pterosaurs, had the same sort of butt-joint metatarsophalangeal joints, and that its feet exactly matched Rotodactylus tracks, but only when the proximal phalanges were all elevated (because they could not be bent), in accord with the findings, but not the conclusions of Clark et al. (1998). Peters (2000a) also showed that many pterosaurs, from Dimorphodon Pteranodon, raised the metatarsals and proximal phalanges in the same way to produce a digitigrade pes. The reduction of pedal digit 5 in derived pterosaurs led to their becoming plantigrade. Beachcomber pterosaurs also rested on their ski-pole like arms and became quadrupeds, but those forelimbs did not provide thrust due to the placement of the hands in front of the shoulder sockets.

Cosesaurus foot in lateral view matches Rotodactylus tracks.

Figure y. Cosesaurus foot in lateral view matches Rotodactylus tracks.

Ironically,
while Witton favors the archosaur model for pterosaur origins, he rejects digitigrade pedes in pterosaurs, a trait widely found in basal dinosaurs and basal bipedal crocs.

Bipedal capability (in the manner of modern bipedal lizards), a narrow chord wing membrane and twin uropatagia solve all sorts of problems introduced and sustained by Mark Witton and the other experts he hangs with. And, there’s fossil evidence for all of this (throughout this blog and reptileevolution.com)! And none for the Witton follies.

Extension and Flexion Forelimb Limitations
Pterosaur arms cannot fully flex if they have large pteroids. The elbow joint also prevents this. Pterosaur arms cannot fully extend due to elbow limitations and the presence of the propatagium, which, as in birds, prevents overextension. These problems limit the ability of the forelimbs to flex and extend completely, like frog legs, to produce the best leap possible.

No Such Limitations in the Hind Limb
Simply leaping (or running and leaping) gets the job done so much better than an exaggerated pushup. Like birds, pterosaurs used their wings to flap and fly. That thrust can be employed during the initial hind limb leap, but not during the initial forelimb leap.

Leaping Lizard
If you want to have a good laugh while watching a rather ordinary lizard leap 3x its body length, check out this YouTube video. Just think how far a pterosaur could leap with those much longer frog-like hind limbs and elongated hips providing power at the femur, the tibia, the metatarsus and the toes in coordinated fashion, accentuated by powerful thrust provided by large flapping wings.

References
Clark J, Hopson J, Hernandez R, Fastovsk D and Montellano M. 1998. Foot posture in a primitive pterosaur. Nature 391:886-889.
Kellner AW, Costa FR, and Rodrigues T. 2012. New Evidence on the pteroid articulation and orientation in pterosaurs. Abstracts, Journal of Vertebrate Paleontology.
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29: 1327-1330.
Peters D 2011.  A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos, 18: 2, 114 —141

A third look at Daemonosaurus

Updated February 28, 2015 with a new skull for Daemonosaurus.

Daemonosaurus is an odd sort of dinosaur that we looked at earlier here and here. Huge teeth. Seems hyper-carnivorous. Apparently not so according to its phylogenetic nesting.

Earlier the large reptile tree nested Daemonosaurus at the base of the Ornithischia (more primitive than Scelidosaurus), not far from Pampadromaeus, Thecodontosaurus and Sacisaurus, among the other phytodinosaur clades. After learning about the palate of Heterodontosaurus, gaining new insights into Pantydraco and revising the scoring of several dinosaur taxa (thanks M. Mortimer), I traced another DGS illustration and created a new reconstruction.

Figure 2 Daemonosaurus skull in 4 views. The new reconstruction is narrower than previously with a new descending pterygoid flange and very few other refinements. The jaw is shorter. The dentary fang(s) appear to slip into that pmx/mx notch as in Heterodontosaurus. A small comb-like dentary tip appears to be a precursor for the predentary found in ornithischians. Gray areas are unknown.

Figure 1. Daemonosaurus skull in 3 views. The new reconstruction is narrower than previously with a new descending pterygoid flange and very few other refinements. The jaw is shorter. The dentary fang(s) appear to slip into that pmx/mx notch as in Heterodontosaurus.

See, I’m always ready to change and ready to learn.
And there’s still more to learn, I’m sure. Here are the new in situ images.

Figure 2. Daemonosaurus with bones colored here. The right side of the skull is flipped. Click to enlarge.

Figure 2. Daemonosaurus with bones colored here. The right side of the skull is flipped. Click to enlarge.

The intermediate length cervicals suggest Daemonosaurus had a neck, midway between that of a typical ornithischian and sauropodomorph.

Daemonosaurus has a high naris, like Herrerasaurus and Massospondylus. The narial depression drops first, then the naris follows on other taxa.

Daemonosaurus has a shorter rostrum than Herrerasaurus and shorter than Pampadromaeus, but not as short as the phytodinosaurs.

The descending quadrate and quadratojugal in Daemonosaurus are also found in Heterodontosaurus and others.

References
Sues H-D, Nesbitt SJ, Berman DS and Henrici AC 2011. A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society Bpublished online 

wiki/Daemonosaurus